Wireless communication environment in recent years faces a problem of a rapid increase in data traffic. Hence, in 3GPP, installing a large number of small cells in a macro cell to increase network density, thereby distributing traffic, has been under study. such a technology utilizing small cells is referred to as small cell enhancement. note that small cells may conceptually include various types of cells (e.g., a femto cell, a nano cell, a pico cell, a micro cell, and the like) that are smaller than a macro cell and are arranged to overlap a macro cell. However, an increase in small cells may cause an increase in inter-cell interference and lead to large power consumption of the entire network; hence, in Patent Literature 1 below, a technology of adaptively setting a small cell in a sleep state has been developed.
In addition, as one way to expand radio resources, utilization of a frequency band of 6 GHz or more, which is called a milli-wave zone, has been under study. However, since the milli-wave zone has strong straightness and exhibits large radio propagation attenuation, utilization in a small cell smaller than a macro cell is expected. Under a situation in which the broad frequency band of the milli-wave zone is not entirely used, part of the frequency band can be turned on/off in the small cell. Further, in regard to a frequency band in an off state, a signal for measurement to enable measurement of quality on the terminal apparatus side is transmitted from a base station.